There are estimated to be 280,000 people in the United States unaware that they are infected with HIV, but this number may drastically decline if the advice of researchers at Yale and several major research hospitals is heeded.

Two studies published today in the New England Journal of Medicine report that routine HIV testing is cost-effective, could help improve the lives of those affected with HIV, and would significantly decrease transmission of the virus. Dr. David Paltiel, a health policy and administration professor in the Department of Epidemiology and Public Health at the Yale School of Medicine, said that screening for HIV is cost-effective compared to screening programs for diabetes and breast cancer, even when performed in settings where fewer than 1 percent of the population is infected.

Historically, Paltiel said, doctors only perform HIV tests when a patient fits a high risk profile for HIV. But this approach is no longer effective, Paltiel said, because the current HIV epidemic is not confined to any one specific group.

“If doctors really had the time to do proper sexual histories, they would, but they don’t,” Paltiel said. “A more effective, efficient and affordable way to detect HIV would be to implement routine HIV testing.”

The guidelines suggested by Paltiel’s study are not completely new. In 2001, the Centers for Disease Control and Prevention issued guidelines for routine HIV testing that never went into effect. Paltiel cited three main reasons for the policy failure — cost concerns, the impracticality of CDC guidelines, and the stigma behind testing, which stems from past programs which singled out specific socioeconomic and demographic subpopulations.

“In our study, we’re offering some practical advice and suggesting that routine HIV testing is quite affordable,” Paltiel said.

The second study, written by Dr. Gillian Sanders, an associate professor at the Duke Clinical Research Institute, reached conclusions similar to those of the University study. Sanders said her study showed that HIV screening provides many benefits and is justifiable in several populations.

“We hope that this work will encourage people to screen for HIV more systematically and more broadly,” said Dr. Douglas Owens, a VA Palo Alto and Stanford University researcher and senior author of the second study. “HIV is chronic and treatment for it would be life-prolonging.”

The VA study suggests that routine screening would lower HIV’s transmission rate by up to 20 percent, depending on the specifics of the screening process.

Both studies were conducted using mathematical modeling, although the studies used two different formulas.

“You can think of this work as putting together a data puzzle,” Paltiel said.

Determining the cost efficiency of HIV testing was no simple task. Paltiel’s study looked at a great deal of information — clinical trials, surveillance data, and economic data on the cost of care and behavioral data. The objective of the model was to synthesize all of this information and see how it translated into economic and epidemiological outcomes, Paltiel said. Researchers in Owens’ study have been working for over four years testing their model.

“You spend a long time testing the model to make sure it behaves in the way you want it to,” Owens said. “You have to check that when you change input, you get out answers that make sense.”

Dr. Rochelle Walensky, assistant professor of medicine at Harvard Medical School and contributor to the Yale study, has conducted trials of routine HIV testing. Working with the Massachusetts Department of Public Health, she helped institute screening in four Massachusetts hospitals in 2002. Initially, she said, only 30 percent of patients accepted testing. But the longer the program was in place, the more likely people were to agree to testing. Through this voluntary testing, Walensky and her colleagues found that 2 percent of those tested were unaware that they were HIV positive.

Another fear when considering routinely screening for HIV is the possibility of false positives, Walensky said. While the standard HIV test involves three separate tests, she said the newer, “rapid test” allows patients to get results in 20 minutes.

“The rapid test is very sensitive and is great for patients,” she said. “But it is not three tests, so when you give a patient the rapid test, you have to tell them that it is preliminary.”

But just because the research suggests routine HIV screening is cost-effective does not mean it is cheap.

“We’ve argued that it’s cost-effective and affordable, not that it saves money,” Paltiel said. “But asking something to pay for itself is bad policy — you want to pay for things that are worth it.”

Funding for routine testing would come from several areas. For some people, insurance could cover the cost while for others, health care systems may pay the bills. Owens said screening will soon become an important issue in the privatized U.S. health care system.

While the need for routine HIV screening in America is currently being evaluated, several countries have already put in place such procedures. Walensky said routine testing programs already exist in Malawi, Botswana and Durban, South Africa.